Digital broadband broadcast networks enable end users to receive digital content including video, audio, data, and so forth. Using a mobile terminal, a user may receive digital content over a wireless digital communications network. For example, a user may receive data such as a broadcast program in a data stream. However, certain data transmissions may be intended for selected end users and not other end users. In this case, a method should be employed to prevent unauthorized access of the data transmission by end users not entitled to receive the data transmission.
Typically, transmitted data is encrypted to prevent unauthorized access to the data. For example, an algorithm may be employed to encrypt the data such that the encrypted data is unreadable. The data may be decrypted at an authorized terminal with the use of a key such as a particular number or string of characters. For the unidirectional communication of data in a digital communications network, a user terminal may receive a signal and filter encrypted services and decrypt the encrypted services with keys that are delivered through the digital communications network. In addition, the keys used to decrypt the data may be encrypted such that a user would need access to both the key for encrypting the data (i.e., a transport encryption key) and the key for encrypting the transport encryption key.
A user terminal may have access to a transmitted program or service for an authorized period of time such as, for example, when a user pays for access to the program or service. In this case, the user gains access to a program or service for a particular length of time, for example, the length of time of the program or service. As an example, a user may wish to view a television program that is one hour long. In this case, the user may purchase access to view the television program during that one hour period which the television program is broadcast.
However, access to the program or service for the user is limited in many ways. For example, the access to the program is time-based such that the keys for decrypting the program or for decrypting transport encryption keys are based on a length of time corresponding to the program. Such a key management system is inefficient since the user is purchasing the keys that provide access to the program or service content and may thus be unable to purchase access to a desired program/service or portion of a program/service.
Thus, a system and method is needed for providing access to a program or service such as programming via a digital communications network in an efficient and flexible manner. Also, a system and method is needed for permitting an end user to gain access to desired portions of a program or service.